Chain of polygalacturonic acid- partially esterified as methyl esters
High Methoxy Pectin (HMP)
Commercial high methoxy pectin: DE 58% to 75%
To form gel, TSS must range between 55-85% and pH 2.8-3.8
Classified into ultrarapid/ rapid set (DE as high as 77)-used in jams & slow set (DE ~58)-used for very acid fruits to avoid premature gelation
Setting time 1-3min to >1h
Not heat reversible
Low Methoxy Pectin (LMP)
DE <50% , Two sub group: Conventional low methoxyl pectin (LMP) and amidated low methoxyl pectin (ALMP)
Form gels in the presence of Ca 2+
LMP less Ca2+ reactive than ALMP=> used as a thickening agent in yoghurt fruit.
ALMP very Ca2+ reactive => assist gelation in low-sugar fruit
Gelation of LM Pectin based on “egg-box” model
Typical pectin uses: Jams,jellies and preserves, Stabilizer and in fermented/directly acidified dairy products. LM pectin gels are heat reversible
Carrageenan
Highly refined extract of seaweed from the rhodophyta family
3 types of carrageenan:
1. Kappa (K-carrageenan)
2. Lambda (ɻ-carrageenan)
3. Lota (ɩ-carrageenan)
Commercial carrageenans are not pure but contain vary amount of the other types
Kappa and lota- carrageenan have the ability to form thermoreversible gels upon cooling of hot aqueous solutions containing various cations; lambda-carrageenan does not form a gel (only act as thickening agent)
Alginate
Derived brown seaweed ( Laminaria hyperborean)
Made up of blocks of D-mannuronic acid (M-block) & L-guluronic (G-block)
Ratio of M:G & MW of polymer determine the solution and gelling properties of alginate
Can form gel in cold water in the presence of Ca ion, the gel is thermo-irreversible
Applications:
1. Provide stabilizing effect in frozen products
2. Act as thickener & stabilizer in beverage
3. Propylene glycol alginate esterified form of alginate has emulsification property commonly used as stabilizer in emulsions
Use for thickening, suspending, stabilizing & modify flow characteristics
Methylcellulose (MC) & HPMC gel when heated & return to their original liquid viscosities when cooled.
Use in fried foods- barrier to oil absorption, stop loss of moisture & improve adhesion of batter
Properties and Application of Gelatin in Food Products
What is Gelatin?
Natural foodstuff
Raw materials: skin (pigskin and hide split) and bone taken from slaughtered animals
Collagen contained is the starting material used for manufacture of gelatin
Amino acid contents: Glycine 33%, Hydroxyproline & Proline 22%, and other 17 amino acid 45%
Composition of edible gelatin: 84-90% Protein, 8-12% Water and 2-4% Mineral Salts
Contain no fat or CHO, no purine or cholesterol and free of all preservatives.
Source and Production of Gelatin Type A: derived from acid processed materials, e.g porkskin
Ø pI at pH 8.0-9.0
1.
2. Place in extraction kettles and hydrolyzed with successive portions of hot water.
3. Filter and evaporate the dilute solution
4. Chill the concentrated solutions to a gel
5. Carefully dry with filtered and conditioned air in drying tunnels/ continuous dryers
6. End product: solid containing ~10% moisture.
7. Test for grade and quality
Type B: derived from alkaline or lime processed materials, e.g cattle or calf hides and ossein
Ø pI in the range 4.8-5.5
1. Calf skin or hide trimmings, wash and treat with lime for 1-3months
2. Limed skins are wash and neutralized with dilute acid.
3. Transfer to kettles and heat with successive portions of hot water
4. Partial hydrolysis of the collagen occurs, result in extracts which are dilute solutions of gelatin
5. Continue Similar to Type A
Ossein gelatin (Type B):
1. Degreased, hard bones, wash and leach with repeated portions of dilute HCl
(Acid reacts with mineral contents of the bone, removed in the acid solution, left ossein)
2. Dry for storage or lime immediately.
3. Follow the procedure outlined for the production of gelatin from calf skin
Gelling Power
Most important property of gelatin: Its ability to form gels in a thermoreversible way
Gelling power is determined by the bloom value -à the measurement of firmness of a standard gel under precisely determined conditions
Bloom value of commercially edible gelatin: 80 – 280
Advantages of high-bloom gelatins
Higher melting and solidification points
More rapid solidification and setting times in the final product
Lower amount needed
Lighter color
Better odor and taste
Which depending on factors of:
Concentration of the gelatin solution
Temperature
Gelling time and gelling temperature
Thermal pre-treatment and duration of treatment
pH of the solution
salt content
Functional Properties of Gelatin
Gel formation
Water binding
Texturising
Thickening
Emulsion formation and stabilization
Foam formation and stabilization
Film formation
Adhesion / cohesion
Protective colloidal function
Note: temperature, salt content and pH are taken into account.
Advantages
Forms thermally reversible gels with water
Gel melting temperature is below body temperature
Gives unique organoleptic properties and flavor release
Disadvantages
Derived from animal hide and bone: Problems regarding kosher and Halal status and also vegetarians
Fish Skin Gelatin
a) Normal gel strength ü Has a normal hydroxyproline content ü Made from fish from warmer water ü Not necessary from fresh water
b) Low or no gel strength ü Has a low hydroxyproline content ü Produced from cold water species ü Used to emulsify vitamin A before spray drying to give another type of microencapsulated product using gelatin
Safety ü Generally Regarded as Safe (GRAS) ü Joint Expert Commission on Food Addictives (JECFA) placed no limit on the use of gelatin in 1970
Hydrocolloids are among the most widely use ingredients in the food industry
- A range of polysaccharides and proteins
- Also known as gums and stabilizers
Functions:- Thickening agents
- Gelling or texturizing agent
- Stabilization of emulsions
- Suspension of particulates
- Control of crystallization
- Encapsulation
- Formation of film
Factors affecting gum properties- Molecular weight
- Monosaccharide composition ( building block
- Type of side chains
- Number of side chains
- Distribution of side chains
Gelation of Hydrocolloids- Some hydrocolloids form gel on heating/ cooling; some require the presence of cations
- Others will form gel under acidic pH + high sugar concentration – High Methoxyl Pectin; Some require alkaline pH
- Thermoreversible gelling agents. Eg gelatin, agar, K-carrageenan, L-carrageenan, LM pectin, Gellan gum, Methy cellulose, Hydropropylmethyl cellulose (HPMC)
- Thermally irreversible gelling agents Eg alginate, starch, konjac, HM pectin
Pectin- Derived from the peel of citrus fruits
- Natural form : protopectin (insoluble)
- Chain of polygalacturonic acid- partially esterified as methyl esters
High Methoxy Pectin (HMP)- Commercial high methoxy pectin: DE 58% to 75%
- To form gel, TSS must range between 55-85% and pH 2.8-3.8
- Classified into ultrarapid/ rapid set (DE as high as 77)-used in jams & slow set (DE ~58)-used for very acid fruits to avoid premature gelation
- Setting time 1-3min to >1h
- Not heat reversible
Low Methoxy Pectin (LMP)- DE <50% , Two sub group: Conventional low methoxyl pectin (LMP) and amidated low methoxyl pectin (ALMP)
- Form gels in the presence of Ca 2+
- LMP less Ca2+ reactive than ALMP=> used as a thickening agent in yoghurt fruit.
- ALMP very Ca2+ reactive => assist gelation in low-sugar fruit
- Gelation of LM Pectin based on “egg-box” model
Typical pectin uses: Jams,jellies and preserves, Stabilizer and in fermented/directly acidified dairy products. LM pectin gels are heat reversibleCarrageenan
Alginate
Gum Arabic
Locust bean gum (LBG)
Guar Gum
Xanthan Gum
Cellulose Derivatives
Properties and Application of Gelatin in Food Products
What is Gelatin?
Source and Production of Gelatin
Type A: derived from acid processed materials, e.g porkskin
Type B: derived from alkaline or lime processed materials, e.g cattle or calf hides and ossein
Gelling Power
Functional Properties of Gelatin
- Gel formation
- Water binding
- Texturising
- Thickening
- Emulsion formation and stabilization
- Foam formation and stabilization
- Film formation
- Adhesion / cohesion
- Protective colloidal function
Note: temperature, salt content and pH are taken into account.Advantages
- Forms thermally reversible gels with water
- Gel melting temperature is below body temperature
- Gives unique organoleptic properties and flavor release
DisadvantagesFish Skin Gelatin
a) Normal gel strength
ü Has a normal hydroxyproline content
ü Made from fish from warmer water
ü Not necessary from fresh water
b) Low or no gel strength
ü Has a low hydroxyproline content
ü Produced from cold water species
ü Used to emulsify vitamin A before spray drying to give another type of microencapsulated product using gelatin
Safety
ü Generally Regarded as Safe (GRAS)
ü Joint Expert Commission on Food Addictives (JECFA) placed no limit on the use of gelatin in 1970